J/AJ/159/230 Stellar occultation by (541132) Leleakuhonua (Buie+, 2020)
A single-chord stellar occultation by the extreme trans-Neptunian object
(541132) Leleakuhonua.
Buie M.W., Leiva R., Keller J.M., Desmars J., Sicardy B., Kavelaars JJ,
Bridges T., Weryk R., Herald D., Haley S.L., Strauss R., Wilde E., Baker R.,
Conway K., Dean B., Dunham M., Estes J.J., Fiechter N., Givot R.,
Glibbery C., Gowe B., Hayman J.N., Ireland O.L., Kehrli M., Moore E.M.,
MacDonald M.A., McCrystal D., Mendoza P., Palmquist B., Rennau S., Schar R.,
Swanson D.J., Terris E.D., Werts H., Wise J.A.
<Astron. J., 159, 230 (2020)>
=2020AJ....159..230B 2020AJ....159..230B
ADC_Keywords: Minor planets; Occultations; Positional data; Photometry
Keywords: Trans-Neptunian objects ; Detached objects ; Stellar occultation ;
Astrometry
Abstract:
A stellar occultation by the extreme large-perihelion trans-Neptunian
object (541132)-Leleakuhonua (also known by the provisional
designation of 2015TG387) was predicted by the Lucky Star project
and observed with the Research and Education Collaborative Occultation
Network (RECON) on 2018-October-20-UT. A single detection and a nearby
nondetection provide constraints for the size and albedo. When a
circular profile is assumed, the radius is r=110-10+14km,
corresponding to a geometric albedo pV=0.21-0.05+0.03, for an
adopted absolute magnitude of HV=5.6, typical of other objects in
dynamically similar orbits. The occultation also provides a
high-precision astrometric constraint.
Description:
The observations for this occultation campaign were part of the
Research and Education Collaborative Occultation Network (RECON)
project (Buie+, 2016AJ....151...73B 2016AJ....151...73B) in collaboration with the Lucky
Star project (see Berard+, 2017AJ....154..144B 2017AJ....154..144B ;
Leiva+, 2017AJ....154..159L 2017AJ....154..159L; Ortiz+, 2017Natur.550..219O 2017Natur.550..219O). At the time
of the event, the cross-track uncertainty was 8000km (0.14"), the
1σ timing uncertainty was 5minutes, and the probability of
success was estimated to be 9% based on the RECON prediction and
participation by all teams. The network covered from -0.11σ to
0.09σ in the cross-track direction. In the down-track direction,
we planned to cover ±2.5σ (30 minutes).
The Canadian sites (C-03 and C-06) use a different camera from the
other RECON sites. The new camera is a QHY174M-GPS (QHY). This device
is based on an sCMOS detector with 1920 by 1200 pixels and a 1ms
readout time and has no mechanical shutter.
At the time of the event, the object was 78.7au from the Sun and
77.7au from the Earth. The trans-Neptunian object (TNO) was moving
24.0km/s on the sky relative to the star (1.5arcsec/hr). The sky-plane
image scale was 56000 km/arcsec. The Gaia DR2 position of the star at
the epoch of the appulse corrected for parallax was
R.A.=00:12:17.891651, decl.=+13:15:07.49674, and J2000 (Gaia DR2
source ID2767694522024100608). The uncertainty in the star position,
dominated by the proper motion uncertainty, was (0.33, 0.31)mas.
The observational details are summarized in Table1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 168 14 Participating Sites
figure2.dat 49 10665 *Observations from the 2018 October 20 occultation
figure4.dat 28 675 Detailed geometry and constraints from the
occultation data
figure5.dat 28 2118 Detailed geometry and constraints from the
occultation data projected in the along-track xv
and cross-track yc directions
figure6.dat 16 102 *Normalized posterior derived from the occultation
analysis
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Note on figure2.dat : All measurements and times are topocentric.
Note on figure6.dat : The x,y values are bin centers for the histogram. All
radius bins are the same size: 2km.
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See also:
II/190 : IRAS Minor Planet Survey (IMPS) (Tedesco 1992)
B/occ : Occultation lights curves (Herald+ 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/other/CoSka/35.45 : Astrometry of minor planets in 2003 (Neslusan+, 2005)
J/A+A/515/A32 : Pluto, Charon, Nix, Hydra occultations 2008-15 (Assafin+,2010)
J/ApJS/189/336 : HST astrometry of TNOs (Benecchi+, 2010)
J/A+A/532/A101 : Lunar occultations of 184 stellar sources (Richichi+, 2011)
J/A+A/541/A142 : Prediction stellar occultations 2008-2015 (Assafin+, 2012)
J/A+A/561/A37 : Prediction of stellar occultations 2012.5-2014 (Camargo+,2014)
J/A+A/584/A96 : Observations of 50 TNOs and Centaurs (Desmars+, 2015)
J/AJ/152/80 : Astrometry of Pluto & trans-Neptunian objects (Holman+, 2016)
J/AJ/152/111 : A 2011-2013 survey of TNOs (Alexandersen+, 2016)
J/AJ/152/221 : New extreme trans-Neptunian objects (Sheppard+, 2016)
J/ApJS/236/18 : OSSOS. VII. TNOs complete data release (Bannister+, 2018)
J/AJ/157/120 : TNOs and Centaurs observed within the DES (Banda-Huarca+, 2019)
J/AJ/157/139 : Inner Oort cloud survey obs.: 2015 TG387 (Sheppard+, 2019)
J/ApJS/244/19 : OSSOS. XII. Subaru/HSC obs. of 65 TNOs (Alexandersen+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- SiteID Observation site identification code
5- 16 A12 --- SiteName Observation site name
18- 25 A8 "HH:MM:SS" Obs.Start UT beginning of the observation
27- 34 A8 "HH:MM:SS" Obs.End UT end of the observation
36- 40 F5.1 --- SUP [0.5/128]? Camera sense-up setting, roughly
equal to an exposure time of SUP/60s (1)
42- 51 F10.6 deg Lat [32.65/49.54] Latitude on the WGS84 datum
53- 63 F11.6 deg Lon [-121.6/-105.2] Longitude on the WGS84 datum
65- 68 I4 m Alt [24/1642] Altitude on the WGS84 datum
70 I1 --- Q [0/5] Quality flag with 1=lowesr, 5=best (2)
72-137 A66 --- PI Observers involved
139-168 A30 --- Com Comments
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Note (1): The entries in SUP column for C-03 and C-06 are actual
exposure times in seconds. See Buie & Keller 2016AJ....151...73B 2016AJ....151...73B for
details on sense-up.
Note (2): Those without data recorded but workable sky conditions are shown with
0.
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Byte-by-byte Description of file: figure2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- SiteID Observation's site identification code
6- 21 F16.8 d JD [2458411/2458412] UT Julian Date of middle of
observation
23- 31 F9.3 s Toffset [18318/20430] Time relative to predicted event
mid-time
33- 40 F8.4 --- Flux [-36.7/64.9] Normalized signal from target star
42- 49 F8.4 --- e_Flux [0.01/763] Uncertainty in Flux
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Byte-by-byte Description of file: figure4.dat
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Bytes Format Units Label Explanations
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1- 7 F7.1 km dx [36687/38986] X (east is positive) offset from
ephemeris (1)
9- 15 F7.1 km dy [19097/19339] Y (north is positive) offset from
ephemeris (1)
17- 28 E12.6 --- prob Integral of normalized probability in 2-D bin
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Note (1): The x,y values are bin centers for the 2D histogram. All bins are
the same size: 3.6x3.6km. Bins with zero probability are omitted.
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Byte-by-byte Description of file: figure5.dat
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Bytes Format Units Label Explanations
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1- 7 F7.3 mas xv [608/610] X (east is positive) down track offset (1)
9- 15 F7.3 mas yc [142/145] Y (north is positive) cross track offset (1)
17- 28 E12.6 --- prob Integral of normalized probability in 2-D bin
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Note (1): The x,y values are bin centers for the 2D histogram. All
bins are the same size: 0.045x0.045mas. Bins with zero probability are
omitted.
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Byte-by-byte Description of file: figure6.dat
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Bytes Format Units Label Explanations
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1- 3 I3 km radius [51/253] Object radius
5- 16 E12.6 --- prob Integral of normalized probability in 2-D bin
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 08-Jun-2020